I think if this was a sim issue that more people would be having the problem. RealFlight G5.5 is one of the more popular (and expensive) sims available, so I find it difficult to believe that the sim itself is causing the issue.

Most planes require a little power during the landing approach. A steep bank requires more power to to maintain level flight then flying straight and level. The size, pitch and speed of the prop can cause flight speed to drop drastically when power is cut. All of these factors (and probably more) are responsible for what you're seeing.

The nose of your plane is dropping because you're not maintaining enough airspeed for the manuever you're making. The plane in the sim will not fly exactly like the model. Each and every model will fly differently as well. To be able to "adjust" the sim to fly exactly like your model you'll need to understand all of the factors acting on the model - lift, drag, etc. Then you'll need to understand how to adjust each of those parameters in the program of the sim. Even after making all of the necassary adjustments the sim and your model will still have some differences. Fortunately, RealFlight is one of those sims that allows you to make the adjustments. Unfortunately, you'll need to gain quite a bit of experience and knowledge to be able to make those adjustments in RealFlight. Good luck.

By the way, holding a certain amount of up elevator (to keep the nose up) is a normal condition for landing. Your goal is to slow the plane close to stall prior to touchdown.